This invention relates to a magnetic recording medium such as a flexible or floppy disk (which may be abbreviated to xe2x80x9cFDxe2x80x9d) for use in a removable type magnetic recording/reproducing device such as a flexible or floppy disk drive (which may be abbreviated to xe2x80x9cFDDxe2x80x9d) and a format method thereof.
As is well known in the art, the FDD of the type described is a device for carrying out data recording and reproducing operations to and from a magnetic disk medium of the FD loaded therein. In recent years, the FDs have been more and more improved to have a larger storage capacity. Specifically, development has been made of FDs having a storage capacity of 128 Mbytes (which may be called large-capacity FDs) in contrast with FDs having a storage capacity of 1 Mbyte or 2 Mbytes (which may be called small-capacity FDs). Following such development, the FDDs have also been improved to accept the large-capacity FDs for data recording and reproducing operations to and from the magnetic disk media of the large-capacity FDs. Furthermore, the large-capacity FDs have been more improved to have a larger storage capacity of 256 Mbytes, 512 Mbytes, . . . , and so on.
Throughout the present specification, FDDs capable of recording/reproducing data for magnetic disk media of the large-capacity FDs alone will be referred to high-density exclusive type FDDs. On the other hand, FDDs capable of recording/reproducing data for magnetic disk media of the small-capacity FDs alone will be called low-density exclusive type FDDs. Furthermore, FDDs capable of recording/reproducing data for magnetic disk media of both the large-capacity and the small-capacity FDs will be called high-density/low-density compatible type FDDs. In addition, the high-density exclusive type FDDs and the high-density/low-density compatible type FDDs will collectively be called high-density type FDDS.
The low-density exclusive type FDD and the high-density type FDD are different in mechanism from each other in several respects, one of which will presently be described. In either FDD, a magnetic head is supported by a carriage which is driven by a drive arrangement to move in a predetermined radial direction with respect to the magnetic disk medium of the FD loaded in the FDD. The difference resides in the structure of the drive arrangement. More specifically, the low-density exclusive type FDD uses a stepping motor as the drive arrangement. On the other hand, the high-density type FDD uses a linear motor such as a voice coil motor (which may be abbreviated to xe2x80x9cVCMxe2x80x9d) as the drive arrangement.
Now, description will be made with respect to the voice coil motor used as the drive arrangement in the high-density type FDD. The voice coil motor comprises a voice coil and a magnetic circuit. The voice coil is disposed on the carriage at a rear side and is wound around a drive axis extending in parallel to the predetermined radial direction. The magnetic circuit generates a magnetic field in a direction intersecting that of an electric current flowing through the voice coil. With this structure, by causing the electric current to flow through the voice coil in a direction intersecting that of the magnetic field generated by the magnetic circuit, a drive force occurs in a direction extending to the drive axis on the basis of interaction of the electric current with the magnetic field. The drive force causes the voice coil motor to move the carriage in the predetermined radial direction.
Another difference between the low-density exclusive type FDD and the high-density type FDD resides in the number of revolutions of a spindle motor for rotating the magnetic disk medium of the FD loaded therein. More specifically, the low-density exclusive type FDD may rotate the magnetic disk medium of the small-capacity FD loaded therein at a low rotation speed of either 300 rpm or 360 rpm. On the other hand, the high-density type FDD can admit, as the PD to be loaded thereinto, either the large-capacity FD alone or both of large-capacity FD and the small-capacity FD. As a result, when the large-capacity FD is loaded in the high-density type FDD, the spindle motor for the high-density type FDD must rotate the magnetic disk medium of the large-capacity FD loaded therein at a high rotation speed of 3600 rpm which is equal to ten or twelve times as large as that of the small-capacity PD.
In the meanwhile, the large-capacity FD generally has an external configuration identical with that of the small-capacity PD. Specifically, both of the large-capacity and the small-capacity FDs have a flat rectangular shape of a width of 90 mm, a length of 94 mm, and a thickness of 3.3 mm in case of a 3.5 -inch type. However, the large-capacity FD has a narrower track width (track pitch) than that of the small-capacity FD. As a result, it is difficult for the large-capacity FD to position a magnetic head of the high-density type FDD on a desired track in the magnetic disk medium thereof in contrast with the small-capacity FD. Accordingly, a servo signal for position detection is preliminarily written in the magnetic disk medium of the large-capacity FD.
In addition, it is necessary for the high-density/low-density compatible type FDD to identify and detect whether the FD loaded therein is the large-capacity FD or the small-capacity PD.
An FD about to be manufactured (which will be called a raw FD) comprises merely a magnetic disk medium having both surfaces coated with magnetic material. In order to enable to make the raw FD useable for an electronic device such as a personal computer or a word processor, it is necessary for the raw FD to partition the magnetic disk medium into a plurality of regions with addresses and to record and manage what information should be written in each region. Such a sequence of processing steps is called a format(ting) or an initialization.
In general, the FD comprises the magnetic disk medium on which a plurality of tracks which are arranged with concentric circles around a center of rotation thereof. The tracks may be arranged in a swirl fashion around the center of rotation. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another.
The formatting is classified into a physical formatting and a logical formatting. The physical formatting determines how data is arranged on the magnetic disk medium. Specifically, the physical formatting determines the total tracks, the total usable tracks, the number of sectors in each track, a medium storage capacity, a format storage capacity, and so on. On the other hand, the logical formatting determines locations where information corresponding to table of contents is written on the magnetic disk medium and assigns addresses to units each of which writes information. The logical formatting is also called a sector formatting.
In the sector formatting, each sector is partitioned into a servo field and a data field. Each sector includes at least a number field indicative of a position thereof and a sector timing mark field for notifying the number field. The number field comprises a sector number field on which a sector number is written and a track number field on which a track number is written. In a conventional sector-formated FD, the sector timing mark field is included in the data field and therefore the number field is also included in the data field. As a result, the data region has a restricted amount for writable data in the sector-formated FD. Inasmuch as the number field is included in the data field, it is necessary to mask the number field so that any user cannot see it. In addition, procedure and processing become complicated after reading of information out of the data field in the sector. Furthermore, the conventional sector-formated FD has no space for storing alteration contents of the magnetic disk medium.
In addition, the sector formatting is performed by using a servo writer and a media formatter. The servo writer partitions first each sector into the servo field and the data field to write the above-mentioned servo signal in the servo field. In this event, the sectors on each track are assigned with sector numbers in the circumferential direction in order. Thereafter, the media formatter carries out test of the sector format and preparation of a defective map. Specifically, since all of the tracks on the magnetic disk medium cannot be used by a user, an area available to the user is restricted. Such an area is referred to as a user data area. Tracks other than the user data area are used as alternate tracks for alternate sectors for replacing defective sectors in the user data area. Such an area for the alternate tracks is an alternate area. The alternate area is generally disposed in the magnetic disk medium in the radial direction inward. In addition, separation of the tracks into the user data area and the alternate area is carried out by the physical formatting. The media formatter first performs test of the sector format to detect the defective sectors on the user data area. Subsequently, the media formatter carries out rearrangement of the sectors except for the defective sectors. Thereafter, the media formatter prepares a defective map. The defective map is a table for entering information indicating where the defective sectors on the user data area are arranged to which alternate sectors in the alternate area. The defective map is stored in a predetermined sector in the alternate area. If the storage capacity of a sector-formatted FD is less than a predetermined specification storage capacity due to the presence of a lot of defective sectors, the sector-formatted FD is discarded because the sector-formatted FD cannot be used.
However, inasmuch the alternate area disposed in the magnetic disk medium in the radial direction inward is used as the alternate sector for the defective sector, it is necessary to move a magnetic head to seek for the alternate sector in the alternate area. As a result, it has a disadvantage in that it takes a long time for accessing the alternate sector.
In order to resolve the above-mentioned disadvantage, a method of setting an alternating sector on every track of the user data area is proposed, for example, in Japanese Unexamined Patent Publication of Tokkai No. Hei 8-45192 or JP-A 8-45192 published on Feb. 16, 1996 which is hereby incorporated herein by reference. In the above-mentioned publication, the alternate sector is set for every track of a disk-shaped recording medium. When a defective sector occurs or is generated, alternate processing is carried out by rearranging the sectors. It is therefore possible to shorten a time required for alternate. Specifically, the rearrangement of the sectors is carried out, as a process starting point, the point after a point where the defective sector is generated.
However, inasmuch as the alternate sector is set for every track regardless of the presence or absence of the defective sector in the above-mentioned publication, problem of degradation in recording efficiency for data arises. In addition, inasmuch as the number of the alternate sectors set in every track is predetermined, it is inevitable that the alternate area is used as the alternate sectors when the defective sectors larger in number than the predetermined number occur in a certain track. In this event, it takes a long time to access the alternate sectors. In other words, it takes a long time to write/read data to/from the disk-shaped recording medium.
As described above, there are various types of the large-capacity FDs so as to have the storage capacity of 128 Mbytes or 256 Mbytes. Throughout the present specification, the large-capacity FD having the storage capacity of 128 Mbytes is called a single-density large-capacity FD while the large-capacity FD having the storage capacity of 256 Mbytes is called a double-density large-capacity FD. Although each of the single-density large-capacity FD and the double-density large-capacity FD has the same line recording density, the same sector format (servo format), and the same number of disk revolution, the single-density large-capacity FD and the double-density large-capacity FD have different track densities from each other. That is, the double-density large-capacity FD has the track density twice as large as that of the single-density large-capacity FD. In addition, the high-density type FDDs capable of recording/reproducing data for magnetic disk media of the single-density large-capacity FDs will be referred to as single-density large-capacity type FDDs. On the other hand, the high-density type FDs capable of recording/reproducing data for magnetic disk media of the double-density large-capacity FDs will be referred to as double-density large-capacity type FDDs.
It is assumed that data are read from the magnetic disk medium of the double-density large-capacity FD by the magnetic head of the single-density large-capacity type FDD. In this event, an output level of the read data is a half of that obtained when data on the magnetic disk medium of the single-density large-capacity FD is read by the magnetic head of the single-density large-capacity type FDD. In addition, it is assumed that data are read from the magnetic disk medium of the single-density large-capacity FD by the magnetic head of the single-density large-capacity type FDD. In this event, an output level of the read data is equivalent to that obtained when data on the magnetic disk medium of the double-density large-capacity FD are read by the magnetic head of the double-density large-capacity type FDD.
On the other hand, it is assumed that data are written in the magnetic disk medium of the double-density large-capacity FD by the magnetic head of the single-density large-capacity type FDD. In this event, a recording level of the data is lower than that obtained when data on the magnetic disk medium of the single-density large-capacity FD are written by the magnetic head of the single-density large-capacity type FDD. In addition, it is presumed that data are written in the magnetic disk medium of the single-density large-capacity FD by the magnetic head of the double-density large-capacity type FDD. In this event, a recording level of the data is equivalent to that obtained when data on the magnetic disk medium of the double-density large-capacity FD are written by the magnetic head of the double-density large-capacity type FDD.
However, once data are written in the magnetic disk medium of the single-density large-capacity FD by the magnetic head of the double-density large-capacity type FDD, the data on the magnetic disk medium of the single-density large-capacity FD only have a recording level equivalent to that of the magnetic disk medium of the single-density large-capacity FD. As a result, when the data on the magnetic disk medium of the single-density large-capacity FD are read by the magnetic head of the single-density large-capacity type FDD, the read data have an output level which is a half of a normal output level. Accordingly, reading of data on the magnetic disk medium of the single-density large-capacity FD by the double-density large-capacity type FDD is no problem, but writing of data on the magnetic disk medium of the single-density large-capacity FD by the double-density large-capacity type FDD is a problem. It is therefore necessary to make the double-density large-capacity type FDD have compatibility of reproduction for the single-density large-capacity FD alone.
In view of such necessity, it is necessary for the high-density type FDD to determine which type the large-capacity FD loaded therein belongs to.
In order to cope with the above-mentioned problem, a large-capacity flexible disk is proposed and disclosed in U.S. patent application Ser. No. 08/854,983, filed May 13, 1997 (now U.S. Pat. No. 5,940,255), entitled xe2x80x9cLARGE-CAPACITY FLEXIBLE DISK AND HIGH-DENSITY TYPE DISK DRIVE USED THEREFORxe2x80x9d, in the name of Tsuneo Uwabo and three others (which was assigned to the present assignee, Mitsumi Electric Co., Ltd.). In the large-capacity flexible disk disclosed in the above-referenced U.S. patent, a case accommodating the magnetic disk medium of the large-capacity FD is provided not only with a large-capacity identifier hole or notch for discriminating the large-capacity FD from a different-capacity FD but also with selectively formed type identifier holes or notches for identifying the type of the large-capacity FD. In addition, it is also disclosed in the above-referenced U.S. patent to provide not only a large-capacity detecting switch for detecting the presence or absence of the above-mentioned large-capacity identifier hole or notch but also type detecting switches for detecting the presence or absence of the type identifier holes or notches.
However, the above-proposed high-density type FDD is disadvantageous in that a lot of parts are required because the high-density type FDD must be provided with the type detecting switches for detecting the type of the large-capacity FD.
In addition, in spite of the large-capacity FDs having the same storage capacity, manufactured large-capacity FDs may have a few different specification for every media makers for manufacturing the large-capacity FDs. In an extreme case, it may happen that the specification of the manufactured large-capacity FD does not satisfy prescribed conditions. Accordingly, it is desirable that the high-density type FDD cannot access the large-capacity FD having the specification that does not the prescribed conditions. In other words, if the high-density type FDD cannot access the large-capacity FD loaded therein because the large-capacity FD is poor, it is desirable that information clue to cause of the poor (hereinafter called poor clue information) is preliminarily stored in the large-capacity FD.
It is therefore an object of this invention to provide a large-capacity flexible disk and a formatting method which are capable of writing a large amount of data in comparison with a conventional large-capacity flexible disk.
It is another object of this invention to provide a large-capacity flexible disk and a formatting method thereof, which are capable of reading information out of a data field without a complicated processing.
It is still another object of this invention to provide a large-capacity flexible disk and a formatting method thereof, in which procedure and processing become easy after reading of information out of a sector.
It is yet another object of this invention to provide a large-capacity flexible disk and a formatting method thereof, which are capable of recognizing alternation contents of a magnetic disk medium of the large-capacity flexible disk in a high-density type flexible disk drive.
It is an object of this invention to provide a disk-shaped recording medium for use in a removable type recording/reproducing device, a sector-formatting method thereof, and a recording/reproducing method, which are capable of accessing at a short time.
It is another object of this invention to provide a disk-shaped recording medium for use in a removable type recording/reproducing device, a sector-formatting method thereof, and a recording/reproducing method, which have a high recording efficiency for data.
It is an object of this invention to provide a disk-shaped recording medium for use in a removable type recording/reproducing device, which is capable of writing/reading data to/from the disk-shaped recording medium in a short time.
It is an object of this invention to provide a disk-shaped recording medium for use in a removable type recording/reproducing device and a sector-formatting method thereof, which are capable of detecting a type of the medium without increase in parts of the removable type recording/reproducing device.
It is another object of this invention to provide ,a disk-shaped recording medium for use in a removable type recording/reproducing device and a sector-formatting method thereof, which are capable of recognizing poor clue information in the removable type recording/reproducing device.
According to a first aspect of the present invention, a large-capacity flexible disk comprises a disk-shaped magnetic disk medium on which a plurality of tracks are arranged with concentric circles. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another. Each sector consists of a servo field and a data field. Each sector includes a number field indicative of a position thereof and a sector timing mark field for notifying the number field. The servo field comprises the sector timing mark field and the number field following the sector timing mark field. The number field includes a space for storing alteration contents of the disk-shaped magnetic disk medium.
According to a second aspect of the present invention, a method of formatting a large-capacity flexible disk comprising a disk-shaped magnetic disk medium comprising: a physical formatting step of arranging a plurality of tracks on the disk-shaped magnetic disk medium with concentric circles and of dividing each track in a circumferential direction into a predetermined number of sectors; and a sector formatting step of partitioning each sector into a servo field and a data field and of making the servo field include a sector timing mark field and a number field indicative of a position thereof following the sector timing mark field. The number field includes a space for storing alteration contents of the disk-shaped magnetic disk medium.
According to a third aspect of the present invention, a disk-shaped recording medium is for use in a removable type recording/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The disk-shaped recording medium comprises a plurality of tracks thereon which are arranged with concentric circles or a spiral fashion around a center of rotation thereof. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another. The sectors on each track are assigned with serial sector numbers in the circumferential direction in order with skipping over any defective sector.
According to a fourth aspect of the present invention, a method is of sector-formatting a disk-shaped recording medium for use in a removable type recording/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The method is carried out after a physical formatting of arranging a plurality of tracks on the disk-shaped recording medium with concentric circles or a spiral fashion around a center of rotation thereof, and of dividing each track in a circumferential direction into a predetermined number of sectors. The method comprises the steps of: partitioning each sector into a servo field and a data field to write a servo signal in the servo field; performing test of a sector format to detect defective sectors; and assigning the sectors on each track with serial sector numbers in the circumferential direction in order with skipping over the defective sectors, thereby carrying out rearrangement of the sectors except for the defective sectors.
According to a fifth aspect of the present invention, a method is of carrying out data recording and reproducing operation to and from a disk-shaped recording medium for use in a removable type recording/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The disk-shaped recording medium comprises a plurality of tracks thereon which are arranged with concentric circles or a spiral fashion around a center of rotation thereof. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another. The method comprises the step of, on reading/writing data from/to the sectors on each track in the circumferential direction in order, sequentially performing reading/writing of data with skipping over any defective sector.
According to a sixth aspect of the present invention, a disk-shaped recording medium is for use in a removable type recording/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The disk-shaped recording medium comprises a plurality of tracks thereon which are arranged with concentric circles or a spiral fashion around a center of rotation thereof. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another. The plurality of tracks are separated in a radial direction into a plurality of zones each of which consists of a plurality of tracks. Each zone includes at least one alternate track.
According to a seventh aspect of the present invention, a disk-shaped recording medium is for use in a removable type recoding/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The disk-shaped recording medium comprises a plurality of tracks thereon which are arranged with concentric circles or a spiral fashion around a center of rotation thereof. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another. The plurality of tracks are separated into a user data area which is available to a user and an alternate area other than the user data area. The alternate area has a specific sector which is an information identification sector for storing historic information in respect to preparation of the disk-shaped recording medium.
According to an eighth aspect of the present invention, a method is of sector-formatting a disk-shaped recording medium for use in a removable type recording/reproducing device for loading and unloading the disk-shaped recording medium to be accessed. The method is carried out after a physical formatting: of arranging a plurality of tracks on the disk-shaped recording medium with concentric circles or a spiral fashion around a center of rotation thereof; of dividing each track in a circumferential direction into a predetermined number of sectors; and of separating the plurality of tracks into a user data area which is available to a user and an alternate area other than the user data area. The method comprises the steps of: partitioning each sector into a servo field and a data field to write a servo signal in the servo field; performing test of a sector format to detect defective sectors on the user data area; carrying out rearrangement of sectors except for the defective sectors; preparing a defective map entering information indicating where the defective sectors on the user data area are arranged to the alternate area to store the defective map in a predetermined sector in the alternate area; and storing historic information in respect to preparation of the disk-shaped recording medium in an information identification sector which is a specific sector in the alternate area.